Butterfly Effect.

The term is closely associated with the work of mathematician and meteorologist Edward Norton Lorenz. He noted that the butterfly effect derives from the illustrative example of the details of a tornado (the exact time of its formation, the same path it takes) being affected by minor disturbances, such as a distant butterfly flapping its wings a few weeks earlier. Lorenz initially used a seagull causing a storm but was persuaded in 1972 to make it more poetic by using a butterfly and tornado. He discovered the effect when he observed runs of his weather model with seemingly insignificantly rounded initial conditions. He found that the weather model could not reproduce the results of runs with initial unrounded conditions. A minimal change in initial conditions produced a significantly different outcome.